When I do 100% water changes I always cup my bettas. Now, since I've owned bettas, I've always put them in the plastic cups that Hillshire Farm meat comes in (after I've washed it). I never really thought about it until now, but I do wash those cups with soap and water. I let them air dry, and use them for a variety of things, but also to cup my bettas. Could the soap be harmful to my boys? They're only in there for about 5 minutes tops, and always with some of the water from the tank. If it is harmful, what else can I do? I don't want to do anything other than cupping when doing water changes.

My understanding is that the soap is still there no matter how well you rinse it off so for safety sake I have cups that I bought that have only ever been rinsed off in hot water. I bought a quarantine tank, one of those rectangular jobs they sell at the pet store for five bucks. I keep my guys in there while cleaning or water changes.

I'm not too concerned about it, I've never had a problem with them. I didn't think about it too much until I started reading here about not cleaning their tanks with soap, which I never have done or will do. But it got me thinking.

i always use the cups my bettas come in. x-X i'm down to one cup, though, cause they're so easy to crack. i've never had issues with cleaning things with soap and using them to cup my bettas. o.0 i'll even was the betta cups with hot soapy water, especially if someone's sick, or if i used it to cup Hyde(i know why he's ill, but my OCD tells me to clean the cup. x-X)

I use a bowl and a cup that have been previously washed with soap (not for a long time) and I haven't had any issues at all...

At home, we always fill our tanks with vases/pitchers/bowls that have been washed with soap and rinsed thoroughly under pure hot water. Never had any issues at all! We have a tetra that's been alive for like eight years XD

Okay, I am glad I'm not the only one doing this. It just never occurred to me to not use cups that have been washed with soap. I all of a sudden started thinking I was doing something horribly wrong or harming my boys... :(

I use an old laundry bucket to do my water changes, so it's probably had a fair few nasty chemicals in it. However, I rinsed it thoroughly with boiling hot water from the kettle, and it has had no effect on any of my fish, my tank cycles or my plants.

Honestly, I don't think a little bit of soap residue is going to hurt your fish. I use bare hands when dealing with some of the cleaning chemicals at work, and none of my fish have become sick or died because of it.